CAIE IGCSE Mathematics Extended number types, HCF and LCM

Practise using number types, prime factorisation, factors, multiples, HCF and LCM to classify numbers and solve integer problems.

Exam points

write integers as products of prime factors using factor trees or factor lists
find HCF or LCM from prime factors, common factors or listed multiples
use square, cube, rational, irrational and reciprocal facts in short calculations

[Maximum number: 2]

Find the lowest common multiple (LCM) of 30 and 75.

150
B1 for answer $150k$
or M1 for prime factors of 30 or 75 seen, a list of multiples of both 30 and 75 with at least 3 of each, $\frac{30\times75}{15}$ oe, or answer $2\times3\times5^2$

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E1.1.1 Identify and use: • natural numbers • integers (positive, zero and question 1